1. Field of the Invention
The present invention relates to an image forming apparatus using electrophotography such as a copier and a printer.
2. Description of the Related Art
The fixing apparatus equipped in an image forming apparatus is desired to be usable over a long time without any problems associated with the fixing process. It is therefore important to improve the accuracy of predicting the lifetime of the fixing apparatus so that the user is prompted to replace the fixing apparatus in an appropriate period. In the fixing apparatus, a fixing rotating member forms a nip portion where recording media are heated as they are conveyed, and rubs against another component at this nip portion. It has been known that the sliding surface of the fixing rotating member deteriorates more with the increase in the number of recording media passed through the nip portion or the number of rotations of the fixing rotating member.
It has been practice to monitor the number of recording media or the rotation time of the fixing rotating member, and to prompt a replacement of the fixing apparatus on an operation panel when a prescribed number of sheets or rotation time is reached, on the basis of which it is assumed that the fixing apparatus's lifetime has expired. The end of lifetime of the fixing apparatus can also be detected, as disclosed by Japanese Patent Application Laid-open No. H11-305579, by monitoring the duration of power application by power application means to heating means.
However, an image forming apparatus that can detect the end of lifetime of the fixing apparatus even more accurately than these configurations is being desired.